At present, a full-colour LED display is widely used for a spliced-type video display, that is, one-piece full-colour LED screen is formed by splicing a series of display modules with a fixed physical resolution. If the resolution of a single display module screen is n*m (that is, a display effective area has n columns of pixels and m lines of pixels), the display resolution of the one-piece full-colour LED screen is K*n columns of pixels and P*m lines of pixels, in the case that the one-piece full-colour LED display screen is formed by splicing K display module screens in a horizontal direction and P display module screens in a longitudinal direction. Moreover, different customers require different screen area, and the number of the spliced display modules of a full-colour LED screen is also unspecified. Therefore, any display area of which the resolution is not less than n*m may be formed. However, the effective resolution of the standard video signal is specified, such as 800*600, 1024*768, 1280*1024, and 1920*1080 or the like. If after a 1080P signal is decoded and decrypted via an HDMI signal, the effective pixel points thereof have 1920 points in the horizontal direction and 1080 points in the longitudinal direction, the video image requires the physical resolution 1920*1080 points of the display device of a terminal for the best display. However, for the display device in which the physical pixel does not reach 1920*1080, the displayed effective area thereof is a part of the image, but the physical pixel points in the full-colour LED display screen are not fixed for site application thereof. Especially, as per the display requirements for the physical points less than 1080P, there are different requirements for the area where the image is displayed, a difference between the video image and the full-colour LED display image is easily caused because the video image cannot be displayed pixel point by pixel point when the full-colour LED display is used for displaying the video image. Furthermore, for a video stream signal of the high resolution, since the pixel clock frequency of the image is too high, the LED display driving circuit suitable for Low Voltage Differential Signalling (LVDS) will suffer from receiving trouble. For example, excessive pixel clock frequency causes excessive transmission bit rate of the LVDS. When the temperature of the circuit rises and the circuit is interfered by noise, the receiving end of the LVDS is unstable, that is, the anti-interference capability becomes bad. Even in a case of a big resolution, such as 1600*1200 resolution, the clock frequency reaches 162.0 Mhz, it cannot be realized to transmit video data through an LVDS protocol.
In order to solve the above problems, in a case where the full-colour LED display displays any resolution, the image is scaled or expanded according to the size of the screen to fit the display of the LED screen. For example, the number of the physical pixel points of the screen is P*K, and the resolution of the image is M*N, so that the image with the resolution of M*N is scaled by P*K. In this way, although a full video screen may be displayed, the processing method increases the complexity of a front-end processing system, and increases the cost, and the image itself will suffer from loss after being processed, which reduces the quality of the image. Furthermore, at present, the technical method of network transmission adopted by the LED limits the data transmission rate of the screen, for example, the transmission rate of a transmission single port of Gbit Ethernet is far less than that in a way of low voltage differential transmission, which is harmful for transmission of high-definition image. Therefore, in order to transmit the high-definition image, multiple Ethernet transmission ports may be added for simultaneous transmission, which also increases the cost.
From the foregoing, in the prior art, the video image is scaled to display video image with different resolutions on the spliced screen, which reduces the quality of the displayed image and makes the processing process complicated.
Currently, no effective solution has been proposed for the problem that the distortion of the displayed image is caused by scaling the video images to display the video images with different resolutions on the spliced screen in the prior art.